Image forming apparatus, image forming method and recording medium

Abstract

An image forming apparatus, which performs image formation by using various colorants, includes a bitmap data generation unit that generates bitmap data, in which each pixel has a gradation value of each color of the colorants, with respect to image formation objects, a label generation unit that generates label information of a relevant pixel for each pixel based on the bitmap data or label information of peripheral pixels of the relevant pixel, and a correction unit that corrects the bitmap data based on the label information. The image formation is performed based on the corrected bitmap data, and the label information includes information on a color of a pixel adjacent to a region to be corrected when the pixel exists in the region to be corrected, and includes information for identifying a color of the relevant pixel when the pixel does not exist in the region to be corrected.

1 . An image forming apparatus for performing image formation by using various colorants, the image processing apparatus comprising:
 a bitmap data generation unit that generates bitmap data, in which each pixel has a gradation value of each color of the colorants, with respect to image formation objects;   a label generation unit that generates label information of a relevant pixel for each pixel based on the bitmap data or label information of peripheral pixels of the relevant pixel; and   a correction unit that corrects the bitmap data based on the label information,   wherein the image formation is performed based on the corrected bitmap data, and   the label information includes information on a color of a pixel adjacent to a region to be corrected when the pixel exists in the region to be corrected, and includes information for identifying a color of the relevant pixel when the pixel does not exist in the region to be corrected.   
   
   
       2 . The image forming apparatus according to  claim 1 , wherein the label information of the pixel existing in the region to be corrected includes distance information from the adjacent pixel. 
   
   
       3 . The image forming apparatus according to  claim 1 , wherein the region to be corrected is a region where the gradation value of a black color of the bitmap data is equal to or larger than a predetermined value while the gradation value of other colors is 0, and does not include a section in which the gradation value of the black color varies. 
   
   
       4 . The image forming apparatus according to  claim 1 , wherein, among the image formation objects, in a region which is in contact with a pixel in which the gradation value of all colors of the bitmap data is 0, and in which the gradation value of a black color of the bitmap data is equal to or larger than a predetermined value while the gradation value of other colors is 0, label information of a pixel in a predetermined range from the pixel being in contact with the region includes distance information from the pixel being in contact with the region. 
   
   
       5 . The image forming apparatus according to  claim 1 , wherein, when the gradation value of the bitmap data of the region to be corrected is a highest value for a black color and is 0 for remaining colors, the correction unit performs the correction by increasing a gradation value of a relevant bitmap data with respect to the color of the adjacent pixel by a predetermined amount, and, when the gradation value of the bitmap data of the region to be corrected is not the highest value in the case of the black color and is 0 in the case of the remaining colors, the correction unit performs the correction by changing the gradation value of the bitmap data into values of each color of a case where a monochromatic black color having the gradation value of the black color is represented by a mixed black color including colors other than the black color. 
   
   
       6 . The image forming apparatus according to  claim 1 , wherein the label generation unit includes:
 a first labeling execution section that generates label information of a relevant image formation object, in which one of plural pieces of first classification information has been assigned to each pixel, based on the bitmap data in which each pixel of the image formation object has the gradation value of each color of the colorants;   a second labeling execution section that updates the label information of the relevant pixel into relevant second classification information, which represents whether the relevant pixel is a candidate to be corrected, by assigning the relevant second classification information to a pixel, to which a predetermined one of the first classification information has been assigned by the first labeling execution section, based on the label information of the peripheral pixels of the relevant pixel; and   a third labeling execution section that updates the label information of the relevant pixel into relevant third classification information, which is used for performing the correction, by assigning the relevant third classification information to a pixel, to which the second classification information representing that the relevant pixel is the candidate to be corrected has been assigned by the second labeling execution section, based on the first classification information assigned to the pixel adjacent to the region to be corrected inclusive of the relevant pixel,   wherein the correction unit performs the correction process of the bitmap data with respect to the pixel, to which the third classification information is assigned, based on the third classification information of the label information, and   the image formation is performed based on the corrected bitmap data.   
   
   
       7 . The image forming apparatus according to  claim 6 , wherein the third classification information includes the color information of the pixel adjacent to the region to be corrected, and
 the third labeling execution section generates the third classification information from the assigned first or third classification information, and assigns the generated third classification information to peripheral pixels of the pixel to which the third classification information has been assigned.   
   
   
       8 . The image forming apparatus according to  claim 7 , wherein the third classification information further includes distance information from the pixel adjacent to the region to be corrected to the pixel to which the third classification information has been assigned. 
   
   
       9 . The image forming apparatus according to  claim 6 , wherein, when the label information of the peripheral pixels is the second classification information, which represents that the relevant pixel is not the candidate to be corrected, the second labeling execution section assigns the second classification information, which represents that the relevant pixel is not the candidate to be corrected, to the pixel. 
   
   
       10 . The image forming apparatus according to  claim 6 , wherein the predetermined one of the first classification information of a pixel, for which the second labeling execution section performs the assignment, is first classification information representing a monochromatic color with the gradation value in a predetermined range, and
 when the first classification information assigned to the peripheral pixel is first classification information representing a monochromatic color identical to a corresponding pixel, and a difference between a gradation value of a relevant peripheral pixel and a gradation value of the corresponding pixel is larger than 0 and is smaller than a predetermined value, the second labeling execution section assigns the second classification information, which represents that the relevant pixel is not the candidate to be corrected, to the corresponding pixel.   
   
   
       11 . The image forming apparatus according to  claim 6 , wherein the correction unit does not perform the correction process with respect to a pixel to which a predetermined one of the third classification information has been assigned. 
   
   
       12 . The image forming apparatus according to  claim 6 , wherein, when the pixel to be corrected has a monochromatic black color and the gradation value of the pixel is a highest value, the correction unit increases a gradation value of the bitmap data of the relevant pixel with respect to the color of the pixel, which is adjacent to the region to be corrected, by a predetermined amount, and
 when the pixel to be corrected has the monochromatic black color and the gradation value of the pixel is not the highest value, the correction unit changes a gradation value of a relevant bitmap data of the relevant pixel into values of each color of a case where a monochromatic black color having the gradation value of the black color is represented by a mixed black color including colors other than the black color.   
   
   
       13 . An image forming method in an image forming apparatus for performing image formation by using various colorants, the image processing method comprising:
 generating bitmap data, in which each pixel has a gradation value of each color of the colorants, with respect to image formation objects;   generating label information of a relevant pixel for each pixel based on the bitmap data or label information of peripheral pixels of the relevant pixel; and   correcting the bitmap data based on the label information,   wherein the image formation is performed based on the corrected bitmap data, and   the label information includes information on a color of a pixel adjacent to a region to be corrected when the pixel exists in the region to be corrected, and includes information for identifying a color of the relevant pixel when the pixel does not exist in the region to be corrected.   
   
   
       14 . A computer readable recording medium storing a print data generation program that causes a host device of an image forming apparatus to execute a process of generating print data for the image forming apparatus that performs image formation by using various colorants, the print data generation program causing the host device to execute:
 generating bitmap data, in which each pixel has a gradation value of each color of the colorants, with respect to image formation objects;   generating label information of a relevant pixel for each pixel based on the bitmap data or label information of peripheral pixels of the relevant pixel; and   correcting the bitmap data based on the label information,   wherein the image formation is performed based on the print data including the corrected bitmap data, and   the label information includes information on a color of a pixel adjacent to a region to be corrected when the pixel exists in the region to be corrected, and includes information for identifying a color of the relevant pixel when the pixel does not exist in the region to be corrected.